v3.25.2
Changes in Accumulated Other Comprehensive Loss (Classification Of Accumulated Other Comprehensive Income Reflected On Consolidated Balance Sheets) (Detail) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Balance, beginning of period $ 1,641.0  
Balance, end of period 1,888.6  
Deferred tax assets, other comprehensive loss 92.3 $ 94.2
Defined Benefit Pension and Postretirement Items    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Balance, beginning of period (244.3)  
Other comprehensive income before reclassifications 0.0  
Net period other comprehensive income 5.4  
Balance, end of period (238.9)  
Defined Benefit Pension and Postretirement Items | Reclassification out of Accumulated Other Comprehensive Income    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Amounts reclassified from accumulated other comprehensive loss 5.4  
Currency Translation Adjustment    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Balance, beginning of period 182.4  
Other comprehensive income before reclassifications 60.0  
Net period other comprehensive income 60.0  
Balance, end of period 242.4  
Currency Translation Adjustment | Reclassification out of Accumulated Other Comprehensive Income    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Amounts reclassified from accumulated other comprehensive loss 0.0  
Accumulated Other Comprehensive Loss    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Balance, beginning of period (61.9)  
Other comprehensive income before reclassifications 60.0  
Net period other comprehensive income 65.4  
Balance, end of period 3.5  
Accumulated Other Comprehensive Loss | Reclassification out of Accumulated Other Comprehensive Income    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Amounts reclassified from accumulated other comprehensive loss $ 5.4